Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description must carry the full burden. It only says 'update', implying mutation, but does not disclose what happens to unmentioned fields, whether updates are atomic, permission requirements, or if there are side effects like plan changes affecting existing subscriptions. This is a significant gap for a mutation tool.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single, clear sentence with no waste. It is concise but lacks a structured breakdown; however, for a simple tool, this is acceptable and earns a 4.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no annotations and a mutation tool, the description is too brief. It does not explain the effect of each parameter, whether updates are partial or full replacement, or any side effects. The presence of 7 parameters, including toggles like is_active and pricing, suggests more context is needed. However, since the schema fully documents parameterstons, the lack of extra behavioral info is a gap.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents all parameters. The description adds no parameter-specific meaning beyond what the schema provides. Baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the verb (update) and resource (pricing plan), making the tool's purpose unambiguous. It does not explicitly distinguish from sibling tools, but the resource is specific enough to avoid confusion with create_plan or update_server.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides no guidance on when to use this tool versus alternatives. There is no mention of prerequisites, side effects, or scenarios where another tool (e.g., create_plan) might be more appropriate.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.